Rubbing in 24th gear (small chainring, large cog) but front derailleur is already up against the seat tube.,

[sms]

I was adjusting the gears on my wife's road bike. It has Shimano Sora
derailleurs.

When the chain is on the largest cog in the rear, and the small chain
ring (it's a 3 x 8), the chain rubs slightly on the inner plate of the
front derailleur cage. But I can't adjust the front derailleur any
further, it's already hitting the seat tube.

Should I change the bottom bracket to one that has a spindle that's a
couple of mm longer to move the chain further out? I'm wondering if they
used the wrong length spindle. The issue is I only need another 2mm or
so but the longer spindles are about 10mm longer.

[Peter Howard]

Would it be ridiculous to suggest putting 2mm worth of shims under the
lip of the drive-side bottom bracket cup? I have often done this to move
a chain line slightly on a SS drivetrain.
https://www.universalcycles.com/shopping/product_details.php?id=2241
is one of my regular online dealers who stocks them.
PH

[Sir Ridesalot]

You can buy a spacer that fits between the drive side cup and the bottom bracket then screw the non-drive side c up in further.

[John B.]

On Thu, 28 Apr 2016 21:41:39 -0700, sms <scharf...@geemail.com>
wrote:

What kind of bottom bracket? The Shimano "outboard bearing" BB uses
"plastic washers" as shims to adjust the chain ring position.
--

Cheers,

John B.

[avag...@gmail.com]

raise/lower deray

or

http://www.toolup.com/product-images/Vise-Grip-23_1.jpg

[avag...@gmail.com]

use 2 ( or more!) always...one holds one bends.

deray metal still malleable ?

[avag...@gmail.com]

knuck knuck .....also poss drill out cage's end rivet n rebolt with appropriate red locktited/nylock fastener

[sms]

Thanks, I wasn't aware of these shims. This should work. I might get by
with jut one of those 0.7mm shims. I had thought of putting a thin
washer on the end of the drive side spindle but didn't think that that
would be a good idea.

[Mark J.]

If the shimming others suggested doesn't work to your satisfaction, you
can look to see the nature of the FD portion that is hitting the seat
tube. If it's not structural (or could still serve its structural
purpose after filing), file/Dremel it down a mm or two.

This is touchy and should be done with care, but I've successfully done
it on at least two Campy FDs (triple with smaller-than-spec small
chainring), with no failure thousands of miles / many shifts later.

Mark J.

[russell...@yahoo.com]

> Should I change the bottom bracket to one that has a spindle that's a
> couple of mm longer to move the chain further out? I'm wondering if they
> used the wrong length spindle. The issue is I only need another 2mm or
> so but the longer spindles are about 10mm longer.

I solved a similar problem on my touring bike by putting in a longer bottom bracket. Shimano sealed bearing kind. Square taper. I was able to find one that was just barely long enough. Not too long. I thought Shimano made many different length bottom brackets. Every 1 or 2 mm between about 100 and 150.